Russian unification was difficult because

a.

of divisions among czars.

c.

of the vastness of the empire and diversity of its people.

b.

of political divisions.

d.

of the opposition of polish forces.

How does the supremacy clause of the u.s. constitution affect the states? o a. it requires each state to establish a supreme court. b. it declares that the federal government can take away state powers if necessary. o c. it allows state governments to overthrow the federal government if necessary. o d. it ensures that the u.s. constitution overrules each state constitution